418 CHEMICAL DYNAMICS 



is ionic; this obviously corresponds very well with the statement 

 in Chap. VIII and elsewhere in this work that the calcium bound 

 in calcium caseinate is not electrolytically dissociated as such. 



In the opinion of Nencki and Sieber (86), Schoumov-Simanovski 

 (123), Pavlov and Parastschuk (95), Savjallov (118), Gevin (38), 

 Migay and Savitsch (83), Van Dam (139) (140) (141), Savitsch 

 (117), Herzog (57), Funk and Niemann (34), Laqueur (71) (72) 

 and Bosworth (12) (13), rennet and pepsin are identical sub- 

 stances, the transformation of casein into paracasein being the 

 first step in hydrolysis or else a side-hydrolysis (135). On the 

 other hand, Hammarsten (43) (44), Hedin (50), Rakoczy (101) 

 and others are of the opinion that rennet and pepsin are dis- 

 tinguishable from one another. The evidence for the identity 

 of the two enzymes lies in the fact that in no way, either quanti- 

 tatively or qualitatively, can the activity of rennet be separated 

 from that of pepsin, statements to the contrary effect (4) (52) 

 (135) (62) (122) (43) having been disproved or else shown to 

 rest upon experimental data obtained under conditions neces- 

 sarily involving inhibition, or apparent inhibition, of the one 

 form of action or of the other (Cf. especially Van Dam, (139) 

 (140) (141)). This is very well illustrated by the following 

 experiment of Morgenroth (85). If mixtures of calcium caseinate 

 and rennet are kept at low temperatures no coagulation occurs, 

 but the digestion process does occur; after these mixtures have 

 been held for some time at the low temperature, if they are heated 

 to 20 degrees they coagulate instantly. Thus the process which 

 underlies the clotting takes place at the lower temperature but 

 cannot be evidenced by actual clotting, until the temperature has 

 risen. It has repeatedly been pointed out (105) (106) (72) that 

 the difference between the behavior of paracasein towards calcium 

 salts and that of casein is essentially this, that calcium para- 

 caseinate is coagulated by calcium salts at lower temperatures 

 than calcium caseinate. 



Now it has been shown by Van Slyke and Hart (143), Geake 

 (36) and Van Slyke and Bosworth (142) that the paracasein 

 freed from its combination with calcium is analytically indis- 

 tinguishable from casein, and Van Slyke and Bosworth have 

 shown that the minimal combining-capacity of paracasein for 

 bases is exactly double that of casein. These facts admit of 

 only one interpretation, namely, that casein is hydrolytically 



